A security researcher disclosed a critical Windows vulnerability enabling system-wide access, defying Microsoft's prior legal warnings over revealing undisclosed software flaws.

Microsoft patches 398 flaws, including exploited CVE-2026-68820 that lets local attackers reach SYSTEM, plus four unauthenticated 9.8 RCEs.

ShieldBreak is a claimed patch bypass for Defender flaw CVE-2026-50656, with a PoC tested on Windows 11 25H2 and Server 2025.